AR Sponsor
Posted: 9/14/2013 4:00:45 AM EDT
|
First ever build and I've hit all the snags possible :-(
After playing musical bolts to find one that will close on my tight DD barrel/go gage...I torque the MI barrel nut to 30 ftlb only to find that it is about 5 degrees past the correct position for the gas tube....no way I can get it to the next position without exceeding the torque specs or breaking something. MI is sending me another barrel nut FOC to see if I have better luck. Assuming this doesn't solve the issue...should I ream the end of the upper a few thousands or is there another way? Just had to build my own...geeeez 
|
|
Quoted:
TOO much. A few thousandths will put it back where it was. A complete notch travel takes only .0027". A third of a notch is only .0009 less than one thousandth. You generally do not even have to go past the thickness of all of the anodizing to adjust it. If I back it off slightly to the point where it aligns (CCW) I can take it off by hand...obviously that won't do. I need to go to the next opening in the nut...which I agree is right around .003" in the bore axis direction (compression). I could be all wet...but I don't see anything in this stack up compressing that much....I tried to tighten with a breaker bar to see what kind of give I could expect and quit before I moved it all that much. I torque the lugs on my car at 100 so I have a good idea what that feels like with my TW.....I felt like I was pretty close to that with the breaker bar and it wasn't moving....FWIW. |
|
Quoted:
More power! Crank that bitch to the next notch and move along. You are not the first to encounter that issue. Happens all the time.  I am sure that is true...but I don't want my second ever post to be: "Hey...anybody know how to re-attach a connector pin lug to a Black Rain upper?" 
|
|
Quoted:
Automotive anti-sieze...you know...the gray crap that seems to multiply as you use it. Quoted:
Quoted:
also---are using the correct grease? Automotive anti-sieze...you know...the gray crap that seems to multiply as you use it. All you need is moly fortified wheel bearing grease. You can get it at ANY parts store. |
|
Quoted:
I am sure you know this, but... You are loosening and re-tightening each time to achieve the position? This. You will have to loosen and re-tighten till you get it to line-up properly as many times as needed, If you have not done so already. If your using the high temp Permtex grease they don't normally have any have any graphite in it, so that should be OK for you. Good Luck. |
|
Quoted:
This. You will have to loosen and re-tighten till you get it to line-up properly as many times as needed, If you have not done so already. If your using the high temp Permtex grease they don't normally have any have any graphite in it, so that should be OK for you. Good Luck. Quoted:
Quoted:
I am sure you know this, but... You are loosening and re-tightening each time to achieve the position? This. You will have to loosen and re-tighten till you get it to line-up properly as many times as needed, If you have not done so already. If your using the high temp Permtex grease they don't normally have any have any graphite in it, so that should be OK for you. Good Luck. While the barrel is out, make sure the face of the upper is square. Not by eyeball, but with a truly flat surface and truly square measurement tool. It can be the table of a good table saw and a simple try square, but make sure you're not having problems because of an upper that's off-true. And make sure there are no blemishes on either side of the barrel's flange, too. Finally, clean ALL of the gunk out of the upper's threads and inspect carefully. You could have a bur or ding in a thread that's made your "5º past perfect at 30 ft/lb" take 30 instead of maybe 10 ft/lb to get to. Weirder things have happened. |
| I find it hard to believe you can't get a hole to line up between 30-80 ft/lbs. Most barrel nuts I have done have not needed any more than 50 ft/lb to align. After you do the tighten/loosen thing three times get a torque wrench and set it to 30 ft/lbs and tighten. If that is not lined up set the wrench to 35 ft/lbs and tighten. If that is not lined up switch to 40 ft/lbs and so on. You cannot back the nut up to line it up. If you pass it up start over again from step one. Also, do not use your torque wrench as a breaker bar. |
|
Anti-seize is what I used from the get-go because it can take the heat and has a very long life span. Be sure it’s on the face of the barrel ring but like you implied it’ll probably find its own way there. Tighten until the barrel nut begins to move and let off giving the threads a moment to cool. Repeat until it’s close but not too close and then bring it into alignment just until an alignment guage can enter the receiver and add a hair more to perfectly align the tube bore.
|
| It took me 10 times loosening and tightening before mine finally lined up. Even then, it was just barely enough to squeeze the gas tube in. But Im about 900rds so far with no failures, so everything is good to go. I also ended up putting around 80lbs or so. Give or take, I also didnt use a torque wrench. But, thats not really needed when your specs are 30-90lbs. You just get passed the 30lbs, and tighten until it works. I kept thinking I was gonna break my upper, but everything has worked great so far. |
AR Sponsor